@Reconstructo,
Existence void of intelligence does not know it exists.
The real Mystery of existence is discovered in that truth.
Without some form of intelligence able to acknowledge and speculate, existence could exist, or not exist, and it would not matter, except for what things have taken place during its progression through time.
The dilemma man finds himself in is that he cannot understand the dynamics around the intelligence he knows he has, and the intelligence he sees in the creation around him. He cannot help but relate the two.
And because of this, man has created many hypothesis regarding the state of intelligence in the origin of existence, forgetting that, in all of the effort, all of this is nothing more than intelligence trying to define itself. It is looking into a mirror of itself, and although recognizing itself, still unable to know its truth and origin.
Intelligence recognizes its attributes, but it cannot see its source. The fact that intelligence even knows it exists, and recognizes the intelligence of design, is testament to the fact of an 'origin of intelligence'.
Just because that origin remains a mystery does not dismiss its reality anymore than a man regarding his reflection in a pool of water knows that he had an origin, even if he had never known his parents or remembers any childhood. This is not a rock looking into creation and not knowing anything of its existence, having no intelligence or ability to recognize anything. This is an intelligence being aware of intelligence all around it, and aware that it is a part of that intelligence at some level.
Inability to plot the point of origin does not interfere with the recognition and appreciation of this intelligence, it simply means that we are not as intelligent as we would like to be.